Three-dimensional multi-shell insulation

ABSTRACT

A three-dimensional multi-shell insulation configured to conform to the shape of a spacecraft component to be insulated. The insulation may have a plurality of nested shell layers that are displaceable relative to each other for providing natural separation between the shell layers when the insulation is used in low-pressure and/or low-gravity space-related applications. To establish the spacing between shell layers, an edge clamp may be operatively coupled to an edge portion on at least one side of each shell layer. The shell layers may have sufficient flexibility and/or may be sufficiently displaceable relative to each other to allow the insulation to be installed or removed from the spacecraft component. One or more restraints may be provided in the space between the shell layers for restricting the relative lateral and/or transverse movement between shell layers for preventing contact. Additive manufacturing may be employed to fabricate the insulation and integrate features.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 15/651,440filed Jul. 17, 2017, which is hereby incorporated herein by reference inits entirety.

TECHNICAL FIELD

The present disclosure relates generally to an insulation, and moreparticularly to insulation formed by three-dimensional nested shells,such as for use in space-related applications.

BACKGROUND

Insulation for spacecraft components helps to guard against the extremeconditions found in outer space, and to control thermal environments,for reliable operation of the spacecraft over long-durations. Forexample, because the exterior temperature of the spacecraft can vary byseveral hundred degrees depending on the spacecraft's exposure to solarradiation, such insulation may be used to thermally isolate the interiorof the spacecraft or specific components to minimize thermal cycling.Multi-layer insulation (MLI) is considered the standard means forproviding a thermal barrier for spacecraft components, and has been usedin space-related applications for more than 50 years. MLI is typicallycomposed of multiple flat layers of metallized Mylar or Kapton film,with a thin netting of an insulating polymer material, such as Dacron orNomex, placed in between each film layer to minimize contact, and thusreduce thermal conduction between layers. However, the performance ofMLI is strongly dependent on the manner in which it is formed andthereafter attached to the spacecraft, because areas where the MLIoverlaps to produce folds, or areas having seams or penetrations, maydramatically reduce insulative performance. Because MLI's performance isso dependent on how well the individual flat panels fit together to forma covering that is free from compressive forces, the MLI blanket panelsmust be designed and sewn together in a custom manner, which is atime-consuming and expensive process. Moreover, MLI's insulativeperformance is difficult to predict due to its dependence on fit and thenegative impact of seams or folds, which introduce unwanted conductiveheat paths. Increasing the number of layers is a typical technique tocompensate for this unpredictability.

SUMMARY

The present disclosure provides a three-dimensional multi-shellinsulation that is configured to conform to the shape of a spacecraftcomponent to be insulated, which helps to minimize the number of seamsor compressive folds between layers, thereby reducing thermal leakageand thermal conduction resulting in improved insulative performance.

More particularly, the multi-shell insulation has a plurality of nestedshell layers of increasing size that are displaceable relative to eachother such that a natural separation between the shell layers forms whenthe insulation is used in low-pressure and/or low-gravity environments,such as outer space. To establish and maintain the spacing between shelllayers, at least one edge clamp may be operatively coupled to at leastone edge portion of each of the shell layers.

The nested shell layers may have sufficient flexibility and/or may besufficiently displaceable relative to each other to allow the insulationto be installed around bends or corners of the spacecraft component andto allow temporary deformation during handling. The insulation also maybe removable to enhance access to the spacecraft component.

Because the shell layers may be able to shift relative to each other,one or more restraints may be provided in the space between the shelllayers to help restrict relative movement and minimize contact betweenshell layers so as to maintain insulative performance.

For example, the restraints may be abutments that act as stops forrestricting too much lateral movement between the shell layers, such aswhen an external lateral force is applied. The abutments also may act asstops for preventing the shell layers from intimate contact along asubstantial portion of each layer, such as when an external compressiveforce is applied. In some embodiments, the abutments of each shell layermay be free from connection to an adjacent shell layer to allow morefreedom of movement between the shell layers, thereby enabling thenatural separation between shell layers, minimizing contact betweenlayers, and enhancing flexibility of the three-dimensional multi-shellinsulation.

In some embodiments, the individual shell layers may be formed with apolymeric material that provides sufficient flexibility for installationand removal. The polymeric material also may provide low thermalconductivity. In addition, the individual shell layers may bemetallized, such as with an aluminum, gold, or other metal coating, toprovide a low emissivity that further enhances insulative performance.

In some embodiments, the insulation may be coupled to the spacecraftcomponent via the at least one edge clamp, which may have a fasteningmechanism integrated therein. The edge clamp also may have a groundingwire integrated therein for reducing weight and ensuring groundingcontact. The edge clamp also may be formed of a low thermal conductivitymaterial for enhancing insulative performance.

In some embodiments, the at least one edge clamp may include at leasttwo edge clamps laterally spaced part along the at least one side of theshell layer to provide at least one passage, or vent, which is in fluidcommunication with the space between shell layers so as to allow gasesto escape during decompression.

In some embodiments, the three-dimensional shell layers may beadditively manufactured to allow the insulation to conform to the shapeof a spacecraft component to be insulated.

Such configuration(s) of the three-dimensional multi-shell insulationhaving customized shells that conform to the shape of the spacecraftcomponent, and which minimize contact between the nested shell layers,may reduce the number of shell layers that are needed for providingcomparable insulative performance to known insulations, such asmulti-layer insulation (MLI), but while also providing reduced mass andimproved cost.

Such configuration(s) may provide precise individual sizing of eachsuccessively nested shell layer to reduce or eliminate compression ofthe layers at bends or folds. In addition, the custom-shaped featuresmay reduce heat leakage by reducing the number of penetrations, such asby providing seams only where desired for facilitating installationand/or removal.

Such configuration(s) utilizing the edge clamp to hold the shell layerstogether, while also spacing them apart and allowing natural separationbetween layer major portions, may minimize the compressive contactbetween the shell layers, which may improve insulative performancecompared to known MLI. In addition, utilizing the edge clamp to hold theshell layers together also may negate sewing multiple seams or edges ascompared to known MLI, which may reduce contamination and foreign objectdebris.

Generally, the three-dimensional multi-shell insulation may utilize aplurality of nested shells to space reflective insulative layers withina custom designed flexible spacecraft insulation that is installable andremovable.

According to one aspect of the present disclosure, a three-dimensionalmulti-shell insulation for insulating at least a portion of a spacecraftis provided that includes: a plurality of nested shell layers configuredto at least partially surround the at least one portion of thespacecraft, each of the plurality of shell layers having layer edgeportions on opposite sides of the shell layer, and a layer major portionextending between the layer edge portions; and at least one edge clampoperatively coupled to the plurality of shell layers at the respectivelayer edge portions on at least one side of the shell layers; whereinthe layer major portions of the plurality of shell layers have at leastone layer major surface configured to be spaced apart from an opposingmajor surface of an adjacent shell layer for minimizing thermalconduction between the shell layers; and wherein the at least one edgeclamp is configured to establish or maintain spacing between therespective layer major surfaces of the shell layers when the insulationis in use in a low-gravity and/or low-pressure environment.

According to another aspect of the present disclosure, athree-dimensional multi-shell insulation may be formed by additivemanufacturing techniques to provide an integrated and unitary insulationproviding significant labor and time savings.

More particularly, according to an aspect of the present disclosure, anadditively manufactured three-dimensional multi-shell insulation forinsulating at least one portion of a spacecraft comprises: a pluralityof nested shell layers formed as a unitary insulation member that isconfigured to at least partially surround the at least one portion ofthe spacecraft; each of the plurality of shell layers having layer edgeportions on opposite sides of the shell layer, and a layer major portionextending between the layer edge portions; the layer major portions ofthe plurality of shell layers having at least one layer major surfaceconfigured to be spaced apart from an opposing layer major surface of anadjacent shell layer for minimizing thermal conduction between the shelllayers; and the layer major portions of adjacent shell layers among theplurality of shell layers each having at least one restraint that isintegrally formed and unitary with the shell layers; wherein therespective restraints of the adjacent shell layers are configured toallow the adjacent shell layers to be displaceable relative to eachother up to a prescribed amount, and to restrict the relativedisplacement between the adjacent shell layers beyond the prescribedamount.

In some embodiments, the additively manufactured three-dimensionalmulti-shell insulation may include an edge binding that is integrallyformed and unitary with the plurality of shell layers at the respectivelayer edge portions on at least one side of the shell layers, whereinthe edge binding is configured to establish spacing between therespective layer major surfaces of adjacent shell layers.

For example, the edge binding may be configured to space the layer majorsurfaces of adjacent shell layers by a sufficient amount to enableelectroless plating of the shell layers after the insulation has beenadditively manufactured.

In some embodiments, the spacing provided by the edge binding may defineat least one flow passage that is in fluid communication with the spacebetween shell layers so as to allow gases to escape from between layers.Optionally, the flow passage(s) may include filter(s) configured tofilter foreign object debris.

In some embodiments, each of the respective restraints may be configuredas a tether, such as a ribbon of material attached between the adjacentlayers. In this manner, as the restraints may be connected betweenlayers, the resulting thermal conductivity may be managed with the useof low thermal conductivity shell material and longer conductive lengthby virtue of wider separation between layers. Although this may resultin a thicker insulation, the resultant structure may be less dense.

Such an additively manufactured three-dimensional multi-shell insulationmay be formed directly from a digital model for achieving a higherprecision of lay-up that optimizes the repeatability and predictability,which otherwise might not be achievable by assembling individual layers.

In some embodiments, the additively manufactured three-dimensionalmulti-shell insulation may incorporate functions for attachment,grounding, and venting that eliminates the need for separate edgeclamps. Grounding paths may be provided by inserting sufficient copperwiring through the assembly. To minimize the thermal conductive leaksthrough the grounding feature, a circuitous path may be used to lengthenthe thermal conductive path while maintaining electrical conductivity.

The following description and the annexed drawings set forth certainillustrative embodiments according to the present disclosure. Theseembodiments are indicative, however, of but a few of the various ways inwhich the principles according to the present disclosure may beemployed. Other objects, advantages and novel features according toaspects of the disclosure will become apparent from the followingdetailed description when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The annexed drawings, which are not necessarily to scale, show variousaspects according to the present disclosure.

FIG. 1A is a perspective view of an exemplary three-dimensionalmulti-shell insulation according to an embodiment of the presentdisclosure, which is shown insulating an exemplary spacecraft component.

FIG. 1B is a cross-sectional side view of a portion of thethree-dimensional multi-shell insulation in FIG. 1A taken about the line1B-1B.

FIG. 2 is a cross-sectional side view of another exemplarythree-dimensional multi-shell insulation according to an embodiment ofthe present disclosure.

DETAILED DESCRIPTION

The principles and aspects according to the present disclosure haveparticular application to insulation used for insulating spacecraftcomponents in space-related applications, and thus will be describedbelow chiefly in this context. It also understood, however, that theprinciples according to the present disclosure may be applicable toinsulation for other applications, such as earth-based cryogenicapplications, or the like, where it is desirable to provide athree-dimensional multi-shell insulation that generally conforms to theshape of the object to be insulated, while minimizing thermal leakageand thermal conduction to improve insulative performance.

FIGS. 1A and 1B show an exemplary three-dimensional multi-shellinsulation 10 for insulating at least a portion of a spacecraft, orspacecraft component 12. As shown, the three-dimensional multi-shellinsulation 10 (also referred to herein as “insulation” or “3DMSI”) maybe configured to conform to the shape of the spacecraft component 12,and thus may have one or more bends, corners, or other suchthree-dimensional configurations in which the insulation 10 extendsalong at least three-axes.

As shown in the illustrated embodiment, the insulation 10 includes aplurality of nested shell layers 14 that may progressively increase insize around at least a portion of the spacecraft component 12. Forexample, the insulation 10 may have at least one outer shell layer 14 aand at least one inner shell layer 14 b, and may have one or more shelllayers 14 therebetween. The shell layers 14 may each have edge portions16 on opposite sides of each shell layer 14, with layer major portions18 extending between the respective layer edge portions 16. The layermajor portions 18 may have at least one layer major surface 20 (e.g., 20a) configured to be spaced apart from an opposing layer major surface(e.g., 20 b) of an adjacent shell layer for minimizing thermalconduction between the shell layers. In exemplary embodiments, the layermajor portions 18 of each nested shell layer 14 may be displaceablerelative to each other for allowing the insulation to billow outwardlysuch that a natural separation forms between the layer major surfaces 20when the insulation 10 is used in low-pressure (e.g., 1×10⁻⁶ to <1×10⁻¹⁷Torr) and/or low gravity (e.g., 10⁻² g) environments, such as when usedin space-related applications.

As shown, at least one edge clamp 22 is provided to operatively coupleto the edge portion 16 on at least one side of each of the shell layers14 so as to set and/or maintain a gap between the shell layers 14 (asshown in FIG. 1B, for example). The edge clamp 22 may be operativelycoupled to one or more of the shell layers 14 by any suitable means. Forexample, as shown in the illustrated embodiment, the edge clamp 22 mayhave one or more posts 24 that are slidably disposed in one or moreholes 26 in the shell layers 14. As shown, the posts 24 may extendtransversely from one or more spacer brackets 25, which may be providedfor facilitating spacing between layers 14. The holes 26 in the shelllayers may be through-holes, and the posts 24 may extend transverselyfrom one side of the shell layer to an opposite side. A fasteningmechanism 28, such as a suitable bonding agent or adhesive, may beutilized to fixedly attach the edge clamp 22 to the shell layers 14. Inexemplary embodiments, the fastening mechanism 28, such as the bondingagent, may be removable so that the edge clamp 22 also may be removable.In some embodiments, the edge clamp 22 may include one or more segments,or the edge clamp may be unitary. It is understood that as used herein,the term “edge clamp” refers to any suitable structure configured toestablish and/or maintain the spacing between the shell layers 14. Thus,although shown as a c-shaped clamp that encloses the edge portions 16 ofthe shell layers, the edge clamp may include other forms of bindings,braces, clasps or other suitable mechanisms for holding the individualshell layers 14 together.

The insulation 10 may include more than one edge clamp 22, such asmultiple edge clamps 22 on one side of the shell layers 14, or one ormore edge clamps 22 on each side of the shell layers 14 (as shown inFIG. 1A, for example). In exemplary embodiments, at least two of theedge clamps 22 may be laterally spaced apart along one or more sides ofthe shell layers 14 to provide at least one fluid passage, or vent, influid communication with one or more of the gaps between the adjacentshell layers 14. For example, as shown in the illustrated embodiment,the venting of gases may flow around the edge clamps 22 and out of thesections of the insulation that are not covered by the clamps 22.Alternatively or additionally, the edge clamps 22 may have one or morepassages extending through the clamp to allow venting of fluid, such asgases, from between the shell layers 14. Such configuration(s) may allowdecompression gases to escape from between the layers 14, which mayoccur during the transition from atmospheric pressures (e.g., earth'satmosphere, such as 760 Torr) to low-pressures (e.g., outer space, suchas 1×10⁻⁶ Torr or less). Optionally, at least one filter may be includedin the fluid passage(s) for filtering foreign object debris.

In exemplary embodiments, the edge clamp 22 may include at least onefastener 32 for operatively coupling the insulation 10 to the anotherportion of the spacecraft, such as a panel component 34. For example, inthe illustrated embodiment, the fastener 32 is configured as aremovable-type fastener, such as a hook-and-loop fastener, for exampleVelcro®, which may have one portion of the fastener 32 attached to theedge clamp 22 and the other portion attached to the panel component 34.Such a configuration may facilitate installation and removal of theinsulation 10. In exemplary embodiments, the edge clamp 22 also may havea grounding wire 36 integrated into the edge clamp for providingelectrical grounding with the spacecraft component 12 and/or the panelcomponent 34. The edge clamp 22 may be formed of a low thermalconductivity material (e.g., have the same or lower thermal conductivitythan the shell layers 14) for enhancing insulative performance. Thegrounding wire 36 may be provided by inserting sufficient conductivewiring, such as copper wire, through the edge clamp. To minimize thethermal conductive leaks through the grounding feature, a circuitouspath may be used to lengthen the thermal conductive path whilemaintaining electrical conductivity.

In exemplary embodiments, the insulation 10 is configured to conform tothe shape of the spacecraft component 12, and also is sufficientlyflexible to enable installation on and/or removal from the spacecraftcomponent 12, such that the insulation 10 may bend or wrap to at leastpartially surround the spacecraft component 12. To facilitateinstallation or removal, the nested shell layers 14 may have sufficientflexibility to enable the layer edge portions 16 on opposite sides ofthe shell layers (e.g., 16 a, 16 b) to be movable relative to eachother. This may allow the insulation 10 to be installed and at leastpartially surround the spacecraft component 12 for insulative purposes,and also may allow the insulation 10 to be removed for enhancing accessto spacecraft component 12. In addition, the ability to conform to thespacecraft component 12 and/or be flexible may enable the insulation 10to provide one or more insulation cowls 40 for insulating communicationschannels, conduits (e.g., 42), or other connection assemblies, such asfor electrical cables, tanks, plumbing, or the like. Such flexibilityand/or the ability to be installed to surround the spacecraft component12 also may reduce the number of seams or gaps provided by theinsulation 10, which may reduce thermal leakage and enhance insulativeperformance. For example, as shown in the illustrated embodiment, theshell layers 14 are configured to at least partially surround thespacecraft component 12 such that opposite edge portions of the shelllayers may be juxtaposed to provide a single seam 38. It is understood,however, that more than one seam may be provided by the edge portions ofthe shell layers, which may depend on the complexity of the spacecraftcomponent and the desirability to install and/or remove the insulation10, as understood by those having skill in the art.

In exemplary embodiments, it also may be beneficial to provide a weavewithin individual shell layers to provide more flexibility at a certainlocation (e.g., for bends at a significant angle, such as 90 degrees).In this manner, the shell layer can be weaved into a lattice similar toforming cloth material. Each individual layer could be woven, whichwould provide more elasticity at the location than a solid thin film.

Because the shell layers 14 may be displaceable relative to each other,an external force could urge the shell layers 14 toward each other tocause contact. For example, an external lateral force could urge theshell layers 14 to shift laterally, such that as those layers extendaround corners or bends the layers could contact each other. Similarly,an external compressive force could urge the shell layers 14 toward eachother in the perpendicular direction such that the shell layers 14 couldcontact each other. Such intimate contact could increase thermalconduction paths and reduce the insulative performance of the insulation10. Therefore, to restrict the amount of lateral and/or transversedisplacement between the shell layers 14, one or more restraints may beprovided in the gaps between the shell layers 14.

As shown in the illustrated embodiment, the one or more restraints mayinclude one or more abutments 50 that act as stops to restrict contactbetween layers 14. As shown, layer major portions 18 may include the oneor more abutments 50, which may protrude from the layer major surfaces20 to extend into the space between the shell layers 14. As shown, theabutments 50 may be configured to provide a stop when they engage theopposing layer major surface 20, which prevents the opposing layer majorsurfaces 20 of adjacent shell layers 14 from contacting each other. Assuch, the abutments 50 may have rounded, pointed, or narrowed ends so asto minimize their contact with the opposing surface. The abutments 50 ofadjacent shell layers 14 also may be configured to provide a stop whenthey engage each other for restricting the amount of relative lateralmovement between layers 14. As such, in exemplary embodiments, theabutments 50 of one shell layer may be laterally offset from theabutments 50 of the opposing shell layer. In the illustrated embodiment,the abutments 50 of adjacent shell layers 14 may be configured in apin-socket like arrangement to restrict shifting in either direction.For example, two or more abutments (e.g., 50 a) on one shell layer 14may straddle one or more abutments (e.g., 50 b) on an adjacent shelllayer to restrict the amount of side-to-side shifting. It is understoodthat although these abutments 50 are shown on at least one side of eachshell layer 14, some layers 14 may be devoid of abutments.

As shown in the illustrated embodiment, the one or more abutments 50 ofeach shell layer 14 are not connected across the gap to an adjacentshell layer. This may reduce the amount of contact between layers, andmay facilitate the ability of the layer major portions 18 to floatrelative to each other, which may further enhance flexibility andfurther enable natural separation between layers, thus improvinginsulative performance. Because the layer major portions 18 may not beconnected via the abutments 50, the edge clamp 22 is configured tomaintain spacing between layers 14. In other words, the insulation 10preferably is not load bearing, and so the precise shaping of the nestedshell layers 14 to avoid layer-to-layer contact while conforming to thespacecraft component 12, and while also providing natural separationbetween layers, allows the layer major surfaces 18 to be devoid ofconnectors or other such structures that would permanently connecttogether and/or force apart the layer major portions 18 of adjacentlayers. Such connectors or other such structures could increaserigidity, increase thermal conduction and reduce insulative performanceof the insulation. Rather, in exemplary embodiments of the insulation10, the abutments 50 preferably do not always contact each other orother portions of the adjacent shell layer, but instead are provided asstops to minimize contact only when the shell layers 14 are shifted,such as when an external force is applied. Accordingly, in exemplaryembodiments, the one or more edge clamps 22 may be provided as the onlymechanism for coupling the plurality of shell layers 14 together. It isunderstood, however, that in other embodiments, one or more structuresor restraints, such as a tether, may be employed between layers to helpconnect layer major portions together, while still providing asufficient amount of displacement between the layer major portions.

In the illustrated embodiment, the one or more abutments 50 of eachshell layer 14 are integrally formed with the shell layer 14, in whichcase the abutments 50 may be made of the same material as the shelllayer 14. Alternatively or additionally, the one or more abutments 50may be attached to each shell layer 14, in which case the abutments 50may be made of the same or different material than the shell layer. Inexemplary embodiments, the abutments 50 may be formed with a materialhaving the same or lower thermal conductivity than the material thatforms the shell layer 14. For example, the thermal conductivity of theshell layers 14 may be less than 0.3 W/m K and preferably less than 0.15W/m K, and the thermal conductivity of the abutments 50 may be less than0.1 W/m K and preferably less than 0.05 W/m K. In exemplary embodiments,the abutments 50 may be made of an aerogel material, such as a polyimideaerogel, which may have a thermal conductivity of about 0.03-0.1 W/m Kand preferably less than 0.03 W/m K. The transverse thickness of one ormore of the abutments 50 may be in the range from about 0.01 mm to about0.05 mm, more particularly about 0.02 mm.

In exemplary embodiments, one or more of the shell layers 14 may be madeof a polymeric material, such as a cyanate ester, epoxy, polyurethane,polyimide, acrylic-based photopolymer (UV cured), or other UV curedpolymers. Alternatively or additionally, one or more of the shell layers14 may be made of metal, such as aluminum or nickel-cobalt. In exemplaryembodiments, the polymeric shell material may have low outgassing, suchas having a total mass loss (TML) of less than 1.0% and a volatilecondensable materials (VCM) of less than 0.1%. Optionally, the polymeroutgassing may be mitigated by vacuum bake out and/or metallizationencapsulation. In exemplary embodiments, the transverse thickness of oneor more of the shell layers 14 may be less than 0.25 mm, moreparticularly less than 0.13 mm, and more particularly less than 0.08 mm.In the illustrated embodiment, the outer shell layer 14 a and the innershell layer 14 b may be thicker than the other shell layers betweenthese two layers (14 a, 14 b). For example, the outer shell layer 14 amay be about 0.13 mm thick, the inner shell layer 14 b may be about 0.08mm thick, and one or more of the shell layers 14 therebetween may eachbe about 0.03 mm thick. Accordingly, the overall transverse thickness ofthe illustrated six-layer insulation 10, including separations betweenlayers, may be about 0.43 mm thick.

In exemplary embodiments, one or more of the shell layers 14 may bemetallized with a thin coating, such as an aluminum, nickel, gold, orother suitable metal coating, to reduce emissivity. For example, theemissivity of one or more of the shell layers 14 may be in the rangefrom about 0.02-0.2, and more particularly less than 0.05. In exemplaryembodiments, the low-emissivity coating may be applied to one or bothsides of the shell layers 14, including the layer major surfaces 20and/or the abutments 50, although the abutments 50 may be devoid of suchlow-emissivity coating to minimize thermal conduction. In theillustrated embodiment, the outer shell layer 14 a may have only theinner side coated, whereas the remaining layers 14 and 14 b may haveboth sides coated. The coating may be applied by any suitable method,such as electroless plating, atomic layer deposition, or vacuumdeposition techniques, as understood by those having skill in the art,

In exemplary embodiments, the individual shell layers 14 may beadditively manufactured to facilitate close conformance to the shape ofthe spacecraft component 12. Any suitable additive manufacturingtechnique may be employed according to well-known methods understood bythose having skill in the art. For example, such additive manufacturingmethods may include: vat photopolymerization techniques (e.g.,stereolithography (SLA), direct light processing (DLP), continuousliquid interface production (CLIP)); powderbed fusion techniques (e.g.,selective layer sintering (SLS), selective laser melting (SLM/DMLS),electron beam melting (EBM), multijet fusion (MJF)); material extrusiontechniques (e.g., fused deposition modeling (FDM)); material jettingtechniques; binder jetting techniques; direct energy depositiontechniques (e.g., laser engineered net shape (LENS), electron beamadditive manufacturing (EBAM); or any other suitable techniques (e.g.,ultrasonic additive manufacturing, etc.).

In accordance with such additive manufacturing methods, an exemplaryprocess for fabricating the insulation 10 may include: i) determiningthe spacecraft component to be insulated, ii) mapping the configurationand/or shape of the spacecraft component into three-dimensionalcoordinate space, iii) based upon the three-dimensional mapping,providing a three-dimensional model of each shell layer 14 individually,or a three-dimensional model of the insulation 10 as a whole, and iv)based upon the three-dimensional model, additively manufacturing eachshell layer 14 individually, or one or more of the shell layerstogether, which also may include additively manufacturing the abutmentsor other structural features with the shell layers.

In exemplary embodiments, the three-dimensional model for the shelllayers 14, or the insulation 10 as a whole, may be defined in anysuitable manner, for example, any computer-readable file or files on anon-transitory computer readable medium that collectively specify theshape, structure, materials, etc. of the insulation. The model mayinclude CAD files, STL files, or the like that provide three-dimensionaldescriptions of the object. For example, the model may include acomputer aided design and manufacturing (CAD/CAM) model havingthree-dimensional numeric coordinates of the entire configuration of theinsulation 10, or each shell layer 14, including both external andinternal surfaces, as well as any internal cavities and openings.Fabrication instructions corresponding to the model may be anycollection of instructions that, when carried out by the additivemanufacturing apparatus, result in the fabrication of the individualshell layers 14 or the insulation 10. For example, fabricationinstructions may include a series of instructions for moving to variousx,y,z coordinates, extruding or forming the build material, controllingfeed rates, etc.

After the individual shell layers 14 have been formed, whether viaadditive manufacturing or other process, the exemplary assembly processmay further include the steps of: i) metallizing shell layers asdesired, ii) optionally attaching one or more abutments to desired shelllayers, and iii) nesting and assembling the shell layers, includingattachment of the one or more edge clamps, to produce thethree-dimensional multi-shell insulation.

Turning now to FIG. 2 , another exemplary embodiment of athree-dimensional multi-shell insulation 110 (also referred to as“insulation” or “3DMSI”) is shown. The insulation 110 may be configuredessentially as a unitary structure that may be formed via additivemanufacturing with one or more integrated edge bindings 122 and/or oneor more integrated restraints 150. The insulation 110 sharessimilarities with the above-described insulation 10, and consequentlythe same reference numerals but indexed by 100 are used to denotestructures corresponding to similar structures in the insulations. Inaddition, the foregoing description of the insulation 10 is equallyapplicable to the insulation 110, and thus aspects of the insulations10, 110 may be substituted for one another or used in conjunction withone another where applicable, except as noted below.

As shown in the illustrated embodiment, the insulation 110 may have oneor more bends, curves, or the like to conform to the shape of thespacecraft component to be insulated (not shown in this embodiment). Theinsulation 110 includes a plurality of nested shell layers 114 thatprogressively increase in size to at least partially surround thespacecraft component. The shell layers 114 may each have edge portions116 on opposite sides of each shell layer 114, with layer major portions118 extending between the respective layer edge portions 116. The layermajor portions 118 may have at least one layer major surface 120 (e.g.,120 a) configured to be spaced apart from an opposing layer majorsurface (e.g., 120 b) of an adjacent shell layer for minimizing thermalconduction between the shell layers.

The insulation 110 may be configured to be sufficiently flexible toenable installation on and/or removal from the spacecraft component,such that the insulation 110 may bend or wrap to at least partiallysurround the spacecraft component. To facilitate installation orremoval, the nested shell layers 114 may have sufficient flexibility toenable the layer edge portions 116 on opposite sides of the shell layersto be movable relative to each other. This may allow the insulation 110to be installed and at least partially surround the spacecraft componentfor insulative purposes, and also may allow the insulation 110 to beremoved for enhancing access to spacecraft component.

In exemplary embodiments, the layer major portions 118 of each nestedshell layer 114 may be displaceable relative to each other for allowingthe insulation to billow outwardly such that a natural separation formsbetween the layer major surfaces 120 when the insulation 110 is used inlow-pressure and/or low gravity environments. To set and/or maintain thespacing between the shell layers 114, the insulation 110 may have one ormore integrated edge bindings 122 that may be disposed toward one ormore of the edge portions 116. In exemplary embodiments, the one or moreintegrated edge bindings 122 may be integral and unitary with the shelllayers 114, and may be formed with the shell layers 114 via additivemanufacturing. The edge bindings 122 may be formed of the same materialor a different material as the shell layers 114, such as a low thermalconductivity material (e.g., having about the same or lower thermalconductivity than the shell layers 14) for enhancing insulativeperformance.

In exemplary embodiments, the integrated edge bindings 122 may belaterally spaced apart along the edge portions 116 of the shell layersto define at least one fluid passage, or vent, in fluid communicationwith one or more of the gaps between the adjacent shell layers 14.Alternatively or additionally, the edge bindings 122 may have one ormore fluid passages extending therethrough to allow ingress or egress offluid between the shell layers 14. Optionally, at least one filter maybe included in the fluid passage(s) for filtering foreign object debris.

As shown in the illustrated embodiment, the insulation 110 may have agrounding wire 136 integrated therein. In exemplary embodiments, thegrounding wire 136 may be formed via additive manufacturing, optionallywith a different material, at essentially the same time as theconstruction of the insulation 110. In other embodiments, the groundingwire 136 may be inserted into the insulation 110 after additivemanufacturing. The grounding wire 136 may be formed by a conductivematerial, such as copper wire. To minimize the thermal conductive leaksthrough the grounding feature, a circuitous path may be used to lengthenthe thermal conductive path while maintaining electrical conductivity.

The insulation 110 also may include one or more fasteners 132 foroperatively coupling the insulation 110 to another portion of thespacecraft. For example, the fastener 132 may be a removable-typefastener, such as a hook-and-loop fastener, for example Velcro®, whichmay have one portion of the fastener 132 attached to the outside of theinsulation 110 and the other portion attached to the other portion ofthe spacecraft.

As shown, the insulation 110 may include one or more restraints 150 forrestricting the amount of lateral and/or transverse displacement betweenthe shell layers 114. The restraints 150 may be unitary with the shelllayers 114, and may be formed via additive manufacturing at essentiallythe same time as the construction of the insulation 110, optionally withthe same or different material as the shell layer 114. In exemplaryembodiments, the one or more restraints 150 may be substantially similarto the above-described abutments 50. For example, in exemplaryembodiments, the one or more restraints may be integral with orconnected to one shell layer 114, but independent from an opposing shelllayer 114, in which case the restraints also may be laterally offset toengage each other when the layers have shifted. Alternatively oradditionally, one or more of the restraints 150 may be connected to bothof the opposing shell layers 114, as shown in the illustratedembodiment. For example, the one or more restraints 150 may beconfigured as a tether, such as a thin ribbon of material, that mayallow for some lateral and transverse displacement of the shell layers114. Preferably, the one or more restraints 150 minimize contact and/orthermal conductivity between layers. For example, as shown in theillustrated embodiment, the restrains 150 may be connected betweenadjacent shell layers 114 such that the connection points are laterallyoffset relative to each other to provide a longer thermal path (e.g., aserpentine or circuitous path), which thereby reduces thermalconduction. In addition, the spacing between shell layers 114 may bewider than the spacing in the above-referenced insulation 10 toaccommodate for these longer thermal paths. Also to reduce thermalconduction, one or more of the restraints 150 may be formed from amaterial having lower conductivity than the shell layers 114, asdiscussed above with reference to the insulation 10.

In exemplary embodiments, the monolithic insulation 110 may beadditively manufactured to facilitate conformance to the shape of thespacecraft component, and the integrated features may provide fasterturnaround times and reduce labor costs. It is understood that anysuitable additive manufacturing technique may be employed to form theinsulation 110 according to well-known methods understood by thosehaving skill in the art, such as those additive manufacturing methodsdescribed above.

In exemplary embodiments, the additive manufacturing technique mayinclude continuous liquid interface production (CLIP). The CLIP processmay begin with a pool of liquid photopolymer resin. The bottom panel ofthe pool enclosure may be transparent to ultraviolet light (e.g., a“window”), and an ultraviolet light beam may pass through the window,illuminating the precise cross-section of the object to be formed. TheUV light causes the resin to solidify, and the object rises slowlyenough to allow resin to flow under and maintain contact with the bottomof solidified-resin to build the object layer by layer. Anoxygen-permeable membrane lies below the resin, which creates a “deadzone” (persistent liquid interface) preventing the resin from attachingto the window. One benefit of the CLIP process is that supportingmaterial or form may not be required for overhangs or complex shapes.

In alternative embodiments, the additive manufacturing technique mayinclude jetted material which is cured by UV light. The polyjet processmay begin with a build platform, and a three-dimensional printer jetsand instantly UV-cures tiny droplets of liquid photopolymer. Fine layersaccumulate on the build platform to create the desired object. Whereoverhangs or complex shapes require support, the three-dimensionalprinter jets a removable support material, which may be removed by wateror solution in a bath. Typically, no post-curing is needed.

In accordance with such additive manufacturing methods, an exemplaryprocess for forming the insulation 110 may include: i) determining thespacecraft component to be insulated, ii) mapping the configurationand/or shape of the spacecraft component into three-dimensionalcoordinate space, iii) based upon the three-dimensional mapping,providing a three-dimensional model of the insulation 110, includingeach shell layer 114, and integrated structures, such as the integratededge bindings 122 and/or integrated restraints 150; and iv) based uponthe three-dimensional model, additively manufacturing the insulation110, including one or more of the integrated features.

After the insulation 110 has been additively manufactured, the shelllayers 114 may be metallized, such as with an aluminum, nickel, gold, orother suitable metal plating for reducing emissivity, as describedabove. An exemplary coating technique may include electroless plating,in which the insulation 110 is submerged in the plating bath and theplating solution flows through the gaps between the shell layers. Inthis manner, the edge binding(s) 122 may be configured to space thelayer major surfaces 122 of adjacent shell layers by a sufficient amountand/or provide sufficiently large fluid passages to allow theelectroless plating solution to flow between shell layers. Alternativelyor additionally, atomic layer deposition may be utilized to coat lowemissivity layers. Before the metallization step, if the additivemanufacturing process utilized removable support material, thesesupports may be dissolved or removed. Thereafter, the fasteningmechanism 132 or other features, such as the grounding wire 136, may beattached or integrated therein.

A three-dimensional multi-shell insulation has been described herein.The insulation may be configured to conform to the shape of a spacecraftcomponent to be insulated. The insulation may have a plurality of nestedshell layers can float relative to each other for providing naturalseparation between the shell layers when the insulation is used inlow-pressure, low-gravity space-related applications. To maintain thespacing between shell layers, at least one edge clamp may be operativelycoupled to an edge portion on at least one side of each shell layer. Theshell layers may have sufficient flexibility and/or may be sufficientlydisplaceable relative to each other to allow the insulation to beinstalled or removed from the spacecraft component. One or morerestraints may be provided in the space between the shell layers forrestricting the relative lateral and/or transverse movement betweenshell layers for preventing contact. Additive manufacturing may beemployed to fabricate the insulation and integrate features.

As used herein, an “operable connection,” or “operable coupling,” is onein which the entities are connected in such a way that the entities mayperform as intended. An operable connection may be a direct connectionor an indirect connection in which an intermediate entity or entitiescooperate or otherwise are part of the connection or are in between theoperably connected entities.

It is to be understood that terms such as “top,” “bottom,” “upper,”“lower,” “left,” “right,” “front,” “rear,” “forward,” “rearward,” andthe like as used herein may refer to an arbitrary frame of reference,rather than to the ordinary gravitational frame of reference.

It is to be understood that all ranges and ratio limits disclosed in thespecification and claims may be combined in any manner. It is to beunderstood that unless specifically stated otherwise, references to “a,”“an,” and/or “the” may include one or more than one, and that referenceto an item in the singular may also include the item in the plural.

The term “about” as used herein refers to any value which lies withinthe range defined by a variation of up to ±10% of the stated value, forexample, ±10%, ±9%, ±8%, ±7%, ±6%, ±5%, ±4%, ±3%, ±2%, ±1%, ±0.01%, or±0.0% of the stated value, as well as values intervening such statedvalues.

The phrase “and/or” should be understood to mean “either or both” of theelements so conjoined, i.e., elements that are conjunctively present insome cases and disjunctively present in other cases. Other elements mayoptionally be present other than the elements specifically identified bythe “and/or” clause, whether related or unrelated to those elementsspecifically identified unless clearly indicated to the contrary. Thus,as a non-limiting example, a reference to “A and/or B,” when used inconjunction with open-ended language such as “comprising” can refer, inone embodiment, to A without B (optionally including elements other thanB); in another embodiment, to B without A (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

The word “or” should be understood to have the same meaning as “and/or”as defined above. For example, when separating items in a list, “or” or“and/or” shall be interpreted as being inclusive, i.e., the inclusion ofat least one, but also including more than one, of a number or list ofelements, and, optionally, additional unlisted items. Only terms clearlyindicated to the contrary, such as “only one of” or “exactly one of,”may refer to the inclusion of exactly one element of a number or list ofelements. In general, the term “or” as used herein shall only beinterpreted as indicating exclusive alternatives (i.e. “one or the otherbut not both”) when preceded by terms of exclusivity, such as “either,”“one of,” “only one of,” or “exactly one of.”

The transitional words or phrases, such as “comprising,” “including,”“carrying,” “having,” “containing,” “involving,” “holding,” and thelike, are to be understood to be open-ended, i.e., to mean including butnot limited to.

Although the present disclosure has shown and described a certainembodiment or embodiments, it is obvious that equivalent alterations andmodifications will occur to others skilled in the art upon the readingand understanding of this specification and the annexed drawings. Inparticular regard to the various functions performed by the abovedescribed elements (components, assemblies, devices, compositions,etc.), the terms (including a reference to a “means”) used to describesuch elements are intended to correspond, unless otherwise indicated, toany element which performs the specified function of the describedelement (i.e., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure which performs thefunction in the herein illustrated exemplary embodiment or embodimentsaccording to the present disclosure. In addition, while a particularfeature according to the present disclosure may have been describedabove with respect to only one or more of several illustratedembodiments, such feature may be combined with one or more otherfeatures of the other embodiments, as may be desired and advantageousfor any given or particular application.

What is claimed is:
 1. An additively manufactured three-dimensionalmulti-shell insulation for insulating at least one portion of aspacecraft, the insulation comprising: a plurality of shell layers ofprogressively increasing size that are nested together and formed as aunitary insulation member that is configured to at least partiallysurround the at least one portion of the spacecraft; each of theplurality of shell layers having layer edge portions on opposite sidesof said each of the plurality of shell layers, and said each of theplurality of shell layers having a layer major portion extending betweenthe layer edge portions; the respective layer major portions of each ofthe plurality of shell layers having at least one layer major surfacethat is configured to be spaced apart from an opposing layer majorsurface of an adjacent shell layer when in use in a low-gravity and/orlow-pressure environment for minimizing thermal conduction between theshell layers; and the respective layer major portions of the respectiveadjacent shell layers of the plurality of shell layers have one or morerestraints that are formed between and unitary with the respectiveadjacent shell layers; wherein the respective one or more restraints ofthe respective adjacent shell layers are configured to allow therespective adjacent shell layers to be displaceable relative to eachother up to a prescribed amount, and are configured to restrict therelative displacement between the respective adjacent shell layersbeyond the prescribed amount; wherein the respective one or morerestraints of the respective adjacent shell layers are configured asrespective ribbons that allow for lateral and transverse displacement ofthe respective adjacent shell layers, and permit the respective adjacentshell layers to billow outwardly when used in a low-pressure and/orlow-gravity environment; and wherein the respective ribbons areunitarily formed with the respective adjacent shell layers at respectiveconnection points, such that the respective connection points of each ofthe respective ribbons are laterally offset relative to each other toprovide a longer thermal path for reducing thermal conduction.
 2. Theadditively manufactured three-dimensional multi-shell insulationaccording to claim 1, wherein the plurality of shell layers havesufficient flexibility to enable the respective layer edge portions onthe opposite sides of the respective shell layers to be movable relativeto each other, such that the insulation is flexibly wrappable around theat least one portion of the spacecraft, thereby allowing the insulationto be installed and at least partially surround the at least one portionof the spacecraft for insulating the at least one portion of thespacecraft, and allowing the insulation to be removed from the at leastone portion of the spacecraft for enhancing access to the at least oneportion of the spacecraft.
 3. The additively manufacturedthree-dimensional multi-shell insulation according to claim 1, whereinthe respective layer major portions of the plurality of shell layers aredisplaceable relative to each other for enhancing the flexibility of theinsulation.
 4. The additively manufactured three-dimensional multi-shellinsulation according to claim 1, wherein each of the plurality of shelllayers has at least one bend for at least partially surrounding the atleast one portion of the spacecraft in three-dimensions.
 5. Theadditively manufactured three-dimensional multi-shell insulationaccording to claim 1, wherein the plurality of shell layers includes anouter shell layer and one or more inner shell layers, the outer shelllayer having a thickness that is greater than a thickness of at leastone of the one or more inner shell layers.
 6. The additivelymanufactured three-dimensional multi-shell insulation according to claim1, wherein a thickness of one or more of the plurality of shell layersis in the range from 0.03 mm to 0.25 mm.
 7. The additively manufacturedthree-dimensional multi-shell insulation according to claim 1, whereineach of the plurality of shell layers is made of a polymeric material.8. The additively manufactured three-dimensional multi-shell insulationaccording to claim 7, wherein the polymeric material includes a cyanateester, epoxy, polyurethane, polyimide, or acrylic-based photopolymer. 9.The additively manufactured three-dimensional multi-shell insulationaccording to claim 7, wherein the polymeric material has low outgassingwith a total mass loss of less than 1.0% and a volatile condensablematerials of less than 0.1%.
 10. The additively manufacturedthree-dimensional multi-shell insulation according to claim 1, wherein athermal conductivity of one or more of the plurality of shell layers isless than 0.3 W/m K.
 11. The additively manufactured three-dimensionalmulti-shell insulation according to claim 1, wherein one or more of theplurality of shell layers is metallized with a low emissivity coating.12. The additively manufactured three-dimensional multi-shell insulationaccording to claim 11, wherein an emissivity of the one or more of theplurality of shell layers metallized with the low emissivity coating isin the range of 0.02 to 0.2.
 13. The additively manufacturedthree-dimensional multi-shell insulation according to claim 1, whereinthe respective adjacent shell layers and the restraints are made with anultra-violet (UV) curable polymer that is capable of being additivelymanufactured by continuous liquid interface production.
 14. Theadditively manufactured three-dimensional multi-shell insulationaccording to claim 1, further comprising: an edge binding that isintegrally formed and unitary with the plurality of shell layers at therespective layer edge portions on at least one side of each of theplurality of shell layers; wherein the edge binding is configured toestablish spacing between the respective layer major surfaces of therespective adjacent shell layers.
 15. The additively manufacturedthree-dimensional multi-shell insulation according to claim 14, whereinthe edge binding is configured to space the respective layer majorsurfaces of the respective adjacent shell layers by a sufficient amountto enable electroless plating of the shell layers after the insulationhas been additively manufactured.
 16. The additively manufacturedthree-dimensional multi-shell insulation according to claim 14, whereinthe edge binding includes at least two edge bindings laterally spacedapart along the at least one side of the respective shell layers toprovide at least one passage for enabling venting of fluid from thespacing between the respective layer major surfaces of the respectiveadjacent shell layers.
 17. The additively manufactured three-dimensionalmulti-shell insulation according to claim 1, wherein the insulation hasat least one fastener for removably attaching the insulation to the atleast one portion of the spacecraft.
 18. The additively manufacturedthree-dimensional multi-shell insulation according to claim 1, whereinthe insulation has a ground wire integrated therein.